Barack Obama missed a golden oppor tunity during the Democratic debate the other night.

Hillary Clinton archly accused him of having represented a Chicago slumlord while practicing law – and Obama immediately went on the defensive.

The Illiniois senator blathered on about a church group that had partnered with the landlord and the number of billable hours he’d submitted, blah, blah, blah.

Pretty weak tea.

What he should have said was something like: YOU want to talk about questionable business connections? I’ve got two words for you – Ron Burkle.

The Wall Street Journal yesterday reported that Bill Clinton stands to reap a $20 million bonanza by finally severing his long-mysterious ties to Burkle, the billionaire financier, supermarket macher and connoisseur of comely young ladies who has long served as Team Clinton’s patron.

Back in 2002, the ex-president signed on as a “senior adviser” to Burkle’s Yucaipa investment funds, performing tasks that never were publicly explained, in return for a hefty profit – at almost no risk – if Yucaipa’s average returns reached 9 percent.

The Journal, quoting documents and sources familiar with the matter, reports that Clinton’s payout could reach as high as $20 million.

Bill Clinton also is a partner, this time investing his own money, in a Yucaipa fund that invests in foreign companies.

And, together with Burkle and an entity connected to the ruler of Dubai – whose US portfolio Yucaipa manages – the former president is a co-owner of the global fund’s general partner.

It’s certainly no mystery why Clinton would want to cash out now – completely apart from the bodacious payday, of course.

His interests in Yucaipa – and particularly its Dubai connection – represent a potential conflict of interest for a potential president of the United States.

To put it mildly.

And not just for a possible president, either.

Remember back in 2006, when Hillary was leading the charge against the proposed takeover of six US ports by a holding company owned by the government of Dubai?

It later developed that Bill was playing the other side of the table, directly advising top Dubai officials on how to overcome negative publicity – and congressional resistance – to the ports deal.

Indeed, he unsuccessfully pressed Dubai to hire his former press secretary to handle PR on the deal. (It did hire the spokesman’s company to help with another US takeover deal.)

Actually, the Journal reports, Bill Clinton apparently ended his “senior adviser” status last year, but waited to cash in his chips until Yucaipa had closed on two lucrative deals that pushed its earnings way past the required threshold – maximizing his payout.

All of this, of course, could end up looking pretty messy as Bill&Hill continue their assault on the White House.

At least as messy as a few billable hours in the service of a particularly ripe Chicago slumlord.